1. Field of the Invention
The present invention relates to a printing apparatus capable of executing duplex printing, and in particular to a printing apparatus creating a drying time for drying ink on a front side of a printing sheet.
2. Discussion of the Background art
In an ink jet printing apparatus capable of executing duplex printing on both sides of a printing sheet, it is known that a user manually inverts a printing sheet after printing an image on a front side surface. Specifically, when a duplex printing mode is designated, a plurality of printing sheets are launched from a sheet feed tray and images of odd number pages are firstly printed onto front side surfaces of the plurality of printing sheets.
Then, the printing sheets with odd number page images are set to the sheet feed tray by the user, and are launched and receive even number page printings on their rear sides. When images are to be printed on more than three pages of the printing sheets, printing of even number page images starts when all of the odd number page images have been printed.
According to such an ink jet printing apparatus, the printing sheet is stained by a friction of a feed roller that pressure contacts the surface of the printing sheet. Also, stein of a sheet feed pad and that caused during a transfer process spread to the printing sheet. In view of these, Japanese Patent Application Laid Open Nos. 2003-226060, and 2203-320727 attempt to suppress these steins.
Specifically, printing data of first and second risky regions of a front side surface to be printed are compared with each other. Then, printing data of a rear side surface is outputted without being inverted when an amount of printing data of the first risky region is smaller than that of the second risky region.
Whereas printing data is inverted and outputted when an amount of printing data of the second risky region is smaller than that of the first risky region. Further, the rear side surface is fed in the same direction as the front side surface when the amount of printing data of the first risky region is smaller than that of the second risky region. The rear side surface is fed in the opposed direction to that of the front side surface when the amount of printing data of the second risky region is smaller than that of the first risky region. As a result, the above-mentioned steins are suppressed.